minor #5593 Updated the profiler matchers article (javiereguiluz)

This PR was squashed before being merged into the 2.3 branch (closes #5593).

Discussion
----------

Updated the profiler matchers article

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all
| Fixed tickets | -

Minor reword to expand some explanations and suggested to make the matcher service private.

Commits
-------

dede183 Updated the profiler matchers article

Author: wouterj

cookbook/profiler/matchers.rst

@@ -4,20 +4,20 @@
 How to Use Matchers to Enable the Profiler Conditionally
 ========================================================
 
-By default, the profiler is only activated in the development environment. But
-it's imaginable that a developer may want to see the profiler even in
-production. Another situation may be that you want to show the profiler only
-when an admin has logged in. You can enable the profiler in these situations
-by using matchers.
+The Symfony profiler is only activated in the development environment to not hurt
+your application performance. However, sometimes it may be useful to conditionally
+enable the profiler in the production environment to assist you in hard to debug
+issues. This behavior is implemented with the **Request Matchers**.
 
 Using the built-in Matcher
 --------------------------
 
-Symfony provides a
+A Request Matcher is a class that checks whether a given ``Request`` instance
+matches a set of conditions. Symfony provides a
 :class:`built-in matcher <Symfony\\Component\\HttpFoundation\\RequestMatcher>`
-which can match paths and IPs. For example, if you want to only show the
-profiler when accessing the page with the ``168.0.0.1`` IP, then you can
-use this configuration:
+which matches paths and IPs. For example, if you want to only show the profiler
+when accessing the page with the ``168.0.0.1`` IP, then you can use this
+configuration:
 
 .. configuration-block::
 
@@ -50,22 +50,24 @@ use this configuration:
 
 You can also set a ``path`` option to define the path on which the profiler
 should be enabled. For instance, setting it to ``^/admin/`` will enable the
-profiler only for the ``/admin/`` URLs.
+profiler only for the URLs which start with ``/admin/``.
 
-Creating a custom Matcher
+Creating a Custom Matcher
 -------------------------
 
-You can also create a custom matcher. This is a service that checks whether
-the profiler should be enabled or not. To create that service, create a class
+Leveraging the concept of Request Matchers you can define a custom matcher to
+enable the profiler conditionally in your application. To do so, create a class
 which implements
 :class:`Symfony\\Component\\HttpFoundation\\RequestMatcherInterface`. This
 interface requires one method:
 :method:`Symfony\\Component\\HttpFoundation\\RequestMatcherInterface::matches`.
-This method returns false to disable the profiler and true to enable the
-profiler.
+This method returns ``false`` when the request doesn't match the conditions and
+``true`` otherwise. Therefore, the custom matcher must return ``false`` to
+disable the profiler and ``true`` to enable it.
 
-To enable the profiler when a ``ROLE_SUPER_ADMIN`` is logged in, you can use
-something like::
+Suppose that the profiler must be enabled whenever a user with a
+``ROLE_SUPER_ADMIN`` is logged in. This is the only code needed for that custom
+matcher::
 
     // src/AppBundle/Profiler/SuperAdminMatcher.php
     namespace AppBundle\Profiler;
@@ -89,24 +91,26 @@ something like::
         }
     }
 
-Then, you need to configure the service:
+Then, configure a new service and set it as ``private`` because the application
+won't use it directly:
 
 .. configuration-block::
 
     .. code-block:: yaml
 
         # app/config/services.yml
         services:
-            app.profiler.matcher.super_admin:
+            app.super_admin_matcher:
                 class: AppBundle\Profiler\SuperAdminMatcher
                 arguments: ["@security.context"]
+                public: false
 
     .. code-block:: xml
 
         <!-- app/config/services.xml -->
         <services>
-            <service id="app.profiler.matcher.super_admin"
-                class="AppBundle\Profiler\SuperAdminMatcher">
+            <service id="app.super_admin_matcher"
+                class="AppBundle\Profiler\SuperAdminMatcher" public="false">
                 <argument type="service" id="security.context" />
         </services>
 
@@ -116,12 +120,15 @@ Then, you need to configure the service:
         use Symfony\Component\DependencyInjection\Definition;
         use Symfony\Component\DependencyInjection\Reference;
 
-        $container->setDefinition('app.profiler.matcher.super_admin', new Definition(
+        $definition = new Definition(
             'AppBundle\Profiler\SuperAdminMatcher',
             array(new Reference('security.context'))
         );
+        $definition->setPublic(false);
 
-Now the service is registered, the only thing left to do is configure the
+        $container->setDefinition('app.super_admin_matcher', $definition);
+
+Once the service is registered, the only thing left to do is configure the
 profiler to use this service as the matcher:
 
 .. configuration-block::
@@ -133,15 +140,15 @@ profiler to use this service as the matcher:
             # ...
             profiler:
                 matcher:
-                    service: app.profiler.matcher.super_admin
+                    service: app.super_admin_matcher
 
     .. code-block:: xml
 
         <!-- app/config/config.xml -->
         <framework:config>
             <!-- ... -->
             <framework:profiler
-                service="app.profiler.matcher.super_admin"
+                service="app.super_admin_matcher"
             />
         </framework:config>
 
@@ -151,6 +158,6 @@ profiler to use this service as the matcher:
         $container->loadFromExtension('framework', array(
             // ...
             'profiler' => array(
-                'service' => 'app.profiler.matcher.super_admin',
+                'service' => 'app.super_admin_matcher',
             ),
         ));